Month: June 2006

The New Yorker magazine has an article on hemispherectomies – surgical procedures which remove half of the cortex, usually in an attempt to cure otherwise life-threating epilepsy.

These operations are usually carried out on children, as remarkably, those in their early years can often develop normal adult skills and abilities if surgery is carried out early enough.

For example, a 2001 book by Antonio Battro (sample chapter: pdf) describes a three year old boy named ‘Nico’ who had the whole of his right hemisphere removed to control life-threatening epilepsy.

Nevertheless, he has developed with very little impairment and has turned out to be a bright and engaging child, despite the fact that a similar operation in adults would be profoundly disabling.

The New Yorker article charts the development of this procedure from the first operation on a human in 1923, to the latest in neurosurgical technology and practice.

Two of the pioneers of the procedure, Dr John Freeman and Dr Ben Carson are also featured, who explain how the team at John Hopkins first tackled a left hemispherectomy. Potentially hazardous, because the left side of the cortex has the majority of the language function in most people.

The article also introduces us to some of the patients who have had the procedure. Christina now drives, graduated from high-school and is studying at university, despite on having only one hemisphere of her brain left.

Link to New Yorker article ‘The Deepest Cut’.pdf of sample chapter from ‘Half a brain is enough’.Link to ‘Half a brain is enough’ book details.

It is generally thought that most visual abilities develop in the first years of life, and if they do not get a chance to develop (usually through eye problems), they cannot be gained later.

For example, people who have had severe congenital cateracts from birth that prevent light from entering the eye, often have trouble making sense of objects if this condition is cured later in life, because the brain has not developed the necessary functions to make sense of objects.

Sacks and Siegel’s letter follows a previous report in Nature that reported on the development of useful vision after 30 years of blindness.

Both of these reports suggest that the brain is more ‘plastic’ (able to reorganise) than was previously thought. This is contrast to ten years ago, when it was largely accepted that the brain developed few new functions after early adulthood.

Link to letter ‘Seeing is believing as brain reveals its adaptability’.

The American Civil Liberties Union has filed a Freedom of Information Act request to try and find out whether the US goverment is using brain scan lie detection technology on suspected terrorists.

The most likely technology to be used for anti-terrorism purposes is Functional Magnetic Resonance Imaging (fMRI), which can produce live, real-time images of people’s brains as they answer questions, view images, listen to sounds, and respond to other stimuli. Two private companies have announced that they will begin to offer “lie detection” services using fMRI as early as this summer. These companies are marketing their services to federal government agencies, including the Department of Defense, Department of Justice, the National Security Agency and the CIA, and to state and local police departments.

While fMRI is certainly a hot-topic at the moment, EEG-based lie detection technology based on the same principle has been around for almost two decades now, and has the advantage of being more portable and considerably cheaper.

It’s interesting that it’s still not clear (publically at least) whether fMRI has any advantages over the existing EEG method, so it will be interesting to see if anything comes out of these enquiries.

New presenter Claudia Hammond kicks off a new series of BBC Radio 4’s All in the Mind with a programme that includes features on decision making, synaesthesia and psychiatric patients writing their own medical notes.

The section on decision making particularly focuses on decisions that involve predicting how the future will turn out and how prior knowledge can both help and hinder our choices.

Neuroscientist Catherine Mulvenna discusses her work on synaesthesia, the condition where the senses are often connected, so, for example, words can be experienced as colours. Mulvenna is using fMRI to look at brain activation in synaesthetes to understand how this happens in the brain.

Finally, clinical psychologist Dr Susan Grey discusses a project where psychiatric patients are asked to contribute to their own medical notes when they are admitted to hospital.

I had the pleasure of working with Dr Grey on the ward she works on, and it’s great to see some of her innovations are becoming recognised. Patients often appreciate the chance to make their own contributions to the medical record, as hospitalisation can sometimes seem disempowering and coercive to many.

Mixing Memory has a fantastic account of recent research on memory distortions in schizophrenia that might explain the unusual experiences and strange ideas that characterise the condition.

Memory distortions are often tested by the use of ‘source monitoring’ or ‘reality monitoring’ experiments (largely invented by Marcia Johnson), where participants are given a list of words and asked to read some of the words out loud, and imagine themselves reading the others out loud.

Afterwards, participants are given a recognition test where they are shown each word and asked whether they read it out, or imagined reading it out.

There are many variations on this theme, but a consistent finding is that those with symptoms of psychosis are more likely to confuse words they imagined reading out with those they said out loud.

The Mixing Memory article tackles a recent study which ran a similar experiment while brain-scanning participants to see which areas would be active when distortions were present.

It turns out that less activity in an area of the frontal lobe called the the medial anterior pre-frontal cortex was linked to more memory distortion errors.

One difficulty though, is that this form of memory distortion is also present in people who have no signs of mental illness but have some delusion-like ideas or experience sensory distortions, suggesting that this effect cannot explain psychosis completely.

Link to ‘Was it Real or Did I Imagine It? Source Monitoring, Schizophrenia, and Our Grip On Reality’